Prior art irrigation systems which include an irrigation line supported by tower assemblies having ground-engaging wheels can be pivoted about a central water supplying tower through the use of water motors associated with each tower assembly, which water motors drive the wheels. Such an arrangement has been found to be highly efficient and effective in driving or pivoting the irrigation line about the source in that the water which is pumped through the irrigation line to irrigate the field can also be used to drive the water motor. This eliminates the need, for example, to have separate electric motors and the appropriate conduits to drive the tower assemblies.
While the prior art water motors work satisfactorily, it has been found that certain areas are prone to wear and abrading due to sand, and other contaminants which are naturally present in the irrigation water. It has been found that such wear is most prominent on metal surfaces which come in contact with rubber or elastomeric seals and O-rings and the like. When such wear and abrading occurs, the water motor must be replaced in its entirety. Accordingly, there exists a need to provide a water motor which overcomes this abrading problem, which water motor is set forth below.